net/mlx5_core: Move completion eqs from mlx5_ib to mlx5_core

Preparation for ethernet driver.
These functions will be used in drivers other than mlx5_ib.

Signed-off-by: Achiad Shochat <achiad@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>